The invention relates to an apparatus for synchronizing the telescopic rams in multi-piston hydraulic elevators.
There is shown in the Swiss patent publication 463 745 a hydraulic or pneumatic synchronous telescopic ram with two or more pistons which are directly loaded by pressure medium and drivable telescopically out of a cylinder, wherein mechanical connecting means engaging between the telescopic parts are present and in each stroke position oblige uniformly distributed part strokes between the successive telescopic parts. Chains or cables, which are not described in more detail and which are to be deflected over rollers, are in particular used as mechanical connecting means.
In the above-described device, chains or cables are provided as mechanical connecting means. In practice, however, only chains have proved themselves up to the present day, because in the case of the properties of cables, especially steel cables, the necessary small bending radii, which can be realized by chains, would lead to premature wear and to strand or cable breakage. In order to be able to bring about the required conditions for a fault-free and safe operation for steel cables, large bending radii of, at the minimum, 30 times the cable diameter would have to be realized, which would lead to a huge increase in the shaft dimensions.
Chains and toothed wheels as deflections have, on the other hand, the disadvantage that they produce vibrations that are transmitted to the pistons and to the car. The general range of use of such stroke pistons can go fully into the region of 5 to 10 tons useful load. That creates the problem that, in the case of increasing useful load, for synchronization of the piston stages forces are reached which can be translated by a corresponding dimensioning of the chains. Nevertheless, the necessary space for the chain deflecting wheels is not enlarged. This means that due to the stronger chains, coarser links are required, which have fewer engagement points for a like tooth number of the chain wheels. Practice shows that the fewer engagement points by the chain in the chain deflecting wheel are effected, the greater are the frequencies that are generated by the combination of chain and chain deflecting wheel. These frequencies are transmitted to the car by way of the pistons and can be unpleasantly felt by the passengers in the form of strong vibrations. The frequencies generated by the chain and chain deflecting wheels can, passed on to pistons and car, excite other car components and parts in terms of frequency, which then become apparent in the form of undesired additional noises. Overall, the travel comfort is negatively influenced to a significant extent by the use of chains and chain deflecting wheels. Steel cables, but especially also chains, must be fundamentally greased before installation in view of their characteristics with respect to corrosion and wear. Moreover, assembling, particularly in the case of chains, is made difficult by their substantial weight. Further assembly aids and an additional person are necessary for assembling. This extra cost reduces productivity during installation.
The present invention has the object of providing a device for the synchronization of telescopic rams in hydraulic elevators of the kind described above, which device does not have the aforesaid disadvantages.
The advantages achieved by the apparatus according to the present invention are that in the case of sheathed synthetic fiber cables substantially smaller bending radii can be realized for like force transmission by comparison with steel cables. The small deflecting radii with chains can be adopted by the synthetic fiber cables or even reduced without needing to have the disadvantageous mechanically coupling points of contact of the chain in the chain deflecting wheel.
Advantageous developments and improvements of the device, for the synchronization of telescopic rams in hydraulic elevators, are possible. Instead of having to use toothed wheels, as required for chains, or large diameter deflecting rollers, as required for steel cables, simple deflecting rollers without roller bearings, for example deflecting rollers of polyamide, are sufficient in the case of use of non-abrasive synthetic fiber cables. Moreover, due to the character of cables of synthetic fibers, the deflecting rollers can be dimensioned to be significantly smaller in their diameters, which means an additional saving of space in the shaft compared to steel cables. Because of the low weight of the lubricant-free synthetic fiber cables, a substantially simpler and thus quicker installation is possible. A sheathing imparts to the synthetic fiber cable a very high resistance to mechanical and chemical damage and to ultraviolet rays. Maintenance, as with steel cables, for example in order to grease the cables, is no longer necessary. Moreover, in view of length extension now able to be disregarded, the synthetic fiber cable no longer has to be readjusted. For increasing the visual effect of an elevator, for example of a panoramic elevator, the sheathing of the synthetic fiber cable can be provided with any desired color or a logo. Finally, the synthetic fiber cable can be equipped in simple mode and manner with a device for precautionary recognition of disruption due to possible wear.